Sr$_{0.9}$K$_{0.1}$Zn$_{1.8}$Mn$_{0.2}$As$_{2}$: a ferromagnetic semiconductor with colossal magnetoresistance

摘要

A bulk diluted magnetic semiconductor (Sr,K)(Zn,Mn)$_{2}$As$_{2}$ wassynthesized with decoupled charge and spin doping. It has a hexagonalCaAl$_{2}$Si$_{2}$-type structure with the (Zn,Mn)$_{2}$As$_{2}$ layer forminga honeycomb-like network. Magnetization measurements show that the sampleundergoes a ferromagnetic transition with a Curie temperature of 12 K and\revision{magnetic moment reaches about 1.5 $\mu_{B}$/Mn under $\mu_0H$ = 5 Tand $T$ = 2 K}. Surprisingly, a colossal negative magnetoresistance, defined as$[\rho(H)-\rho(0)]/\rho(0)$, up to $-$38\% under a low field of $\mu_0H$ = 0.1T and to $-$99.8\% under $\mu_0H$ = 5 T, was observed at $T$ = 2 K. Thecolossal magnetoresistance can be explained based on the Anderson localizationtheory.